Is the war on invasive species really worth fighting?

Lake Improvement District
A sign at Marion Lake in Otter Tail county warns boaters against spreading aquatic invasive species.
Dan Gunderson | MPR News

The country is at war — with plants. And fish. And bugs.

Non-native species are being targeted in backyards, big lakes and national parks. Some of the removal plans make sense, experts say, but things have also gotten out of hand. Massive amounts of money are being poured into efforts that may not be effective or even necessary.

"We've declared war on invasive species," Mark Davis, a professor of Terrestrial Ecology and Animal Behavior at Macalester said. "And usually when the U.S. declares war on something, the only thing that's guaranteed is spending a lot of money."

Davis and Mike Hoff, an Invasive Species Coordinator in the Midwest for the U.S. Fish and Wildlife Service, joined MPR News editor Michael Edgerly to discuss non-native species and some of the misconceptions about them.

The first point to note is an important distinction: Not all non-native species are invasive species.

"Technically, and also legally, the term 'invasive' is supposed to be restricted only to non-native species that cause harm. That could be harm to human health, economic harm or ecological harm," Davis said. "For many people, the term 'invasive' and 'non-native' are used interchangeably, and one of the things we've been trying to emphasize is a much more nuanced approach."

Hoff echoed that sentiment, saying that only 10 percent of non-native species that are introduced to an area actually survive and become established. From there, only 10 percent of those become invasive — causing harm to an ecosystem, economy or human health.

When it comes to assessing a species, people should concentrate on what it does, not where it came from, Davis said. In some cases, native species can cause significantly more harm, like the mountain pine beetle, "which is killing more trees than any other insect in this part of the world, but which is native."

Hoff works in the area of risk assessment, trying to help the U.S. Fish and Wildlife Service determine what species pose enough of a threat to address. One species they're studying closely is Asian Carp, which they are trying to prevent from entering the Great Lakes.

The carp "was introduced into the United States for cultural purposes. Basically, it was such a good filter feeder, it would keep the catfish ponds very clean. Better quality meant better product," Hoff said. "Eventually, there were some escapes because of the flooding and they became established in parts of the Mississippi. They have expanded in their range, and there are occasionally some collected in Minnesota waters like the St. Croix River, Mississippi River, Minnesota River, but they haven't become nearly as abundant as the Illinois River."

So what can be done? Research continues on that point.

Meanwhile, plants like buckthorn or garlic mustard may not actually be the villains Minnesota gardeners have made them out to be, Davis said.

"They're Minnesota plants now, no matter what you call them. They're here. They're common Minnesota plants and they're not driving any plants to extinction," he said. "There are a lot of misunderstandings about what many non-native species do."

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